It is known how to close infusion bags exclusively with a string. For this, the corners on top of the infusion bag are first folded down and then the middle part is folded over the folded down corners to make the closure of the infusion bag reliable. This closure is secured by a string that has several ways of being attached.
In one known embodiment in German Utility Model 296 13 448, the string on the top part of the infusion bag is attached there by means of a separate attachment string. This connection between the end of the string and the infusion bag cannot withstand high stresses and is technically expensive.
To create a simple way of attaching the string, it is known from EP 0 807 579 how to provide the folded top part with two recesses and place the infusion bag next to a tensed string in such a way that it runs at the height of the recesses and a tucking needle can be passed through each of the recesses, take the string and pull it through the recesses with both its ends. The free ends of the string pulled through the recesses in the infusion bag are attached to the tag, for example by welding or tacking. The disadvantage of this is that the attachment is loose and therefore not secure, and it is possible for the folded down areas on the top part to come unfolded, so the contents of the infusion bag can fall out or a loss of aroma and freshness can occur.
EP 0 691 268 discloses a string closure in which a needle goes through a single hole in the top part of the infusion bag, grasps the string behind and pulls it through the hole, forming a noose, which is then used to make a knot. The disadvantage of this is that it does not make sure that the folded down corners and the middle of the top part folded down over it are grasped together and with the bag by the string connection and are connected by the knot formed. The closure itself is not secure enough during folding, perforating and stringing with high manufacturing precision.